In the past, an imaging apparatus for diagnosis has been used for diagnosis of arteriosclerosis, for diagnosis before an operation or medical procedure, at the time of an endovascular treatment by a high functional catheter such as a balloon catheter, a stent and the like or to confirm results after an operation or medical procedure.
An example of a representative imaging apparatus for diagnosis is an intravascular ultrasound (IVUS) apparatus for diagnosis. Generally, the intravascular ultrasound apparatus for diagnosis is an apparatus which emanates an ultrasound wave inside a blood vessel while rotating a transmitting and receiving unit in a state of inserting an ultrasound probe unit installed with the transmitting and receiving unit composed of an ultrasound vibrator inside a blood vessel, which carries out a radial scan by receiving a reflection wave from the living body and which visualizes a cross-sectional image of a blood vessel based on the intensity of an ultrasound echo signal generated by applying a process of amplification, detection or the like.
An example of another imaging apparatus for diagnosis is an optical coherent tomography (OCT) apparatus for diagnosis which carries out diagnosis by utilizing coherency of light. An example is disclosed in Japanese unexamined Patent Publication No. 2001-79007.
The optical coherent tomography apparatus for diagnosis is an apparatus in which measurement light is emitted inside a blood vessel while rotating a transmitting and receiving unit in a state of inserting an optical probe unit which is built-in with a transmitting and receiving unit mounted with an optical lens and an optical mirror at the distal end and an optical fiber inside the blood vessel, a radial scan is carried out by light-receiving reflected light from a biological tissue, and a cross-sectional image of the blood vessel based on interference light is visualized by making the reflected light obtained depending on this and a reference light split from the measurement light beforehand interfere each other.
Further, recently, as an improved version of the optical coherent tomography apparatus for diagnosis, there has been developed an optical frequency domain imaging (OFDI) apparatus for diagnosis utilizing wavelength sweep.
With respect to the optical frequency domain imaging (OFDI) apparatus for diagnosis utilizing wavelength sweep, the basic constitution thereof is similar as that of the optical coherent tomography (OCT) apparatus for diagnosis, but there exists a feature in an aspect that a light source having a longer wavelength compared with the optical coherent tomography (OCT) apparatus for diagnosis is used and also, light having different wavelengths is emitted continuously. Then, a mechanism for variably changing the optical path length of the reference light is made unnecessary by employing a construction in which reflected-light intensity at each point in the depth direction of the biological tissue is found out by frequency analysis of the interference light.
It should be noted in this description hereinafter that the intravascular ultrasound (IVUS) apparatus for diagnosis, the optical coherent tomography (OCT) apparatus for diagnosis and the optical frequency domain imaging (OFDI) apparatus for diagnosis utilizing wavelength sweep are named generically and to be referred to as an “imaging apparatus for diagnosis”.
Generally, the multiple cross-sectional images visualized by using such an imaging apparatus for diagnosis are displayed on a display apparatus in real time during the radial operation of the transmitting and receiving unit. Also, the multiple cross-sectional images displayed on the display apparatus (or line data used for visualizing the cross-sectional images) are stored concurrently in a predetermined memory and if required, the system allows them to be redisplayed on the display apparatus as many times as requested.
However, in an imaging apparatus for diagnosis known up until now, the apparatus was constructed so that multiple cross-sectional images (or line data) which are visualized during an interval from the start of the radial operation to the termination thereof are stored at a predetermined position inside the memory re-displayably in sequence regardless of the presence or absence of variation in operation speed of the radial operation of the transmitting and receiving unit (specifically, axial direction motion speed along the blood vessel).
Consequently, in case of redisplaying the multiple cross-sectional images on the display apparatus, there used to be employed a constitution in which the respective cross-sectional images are to be displayed without regard to the position in the actual axial direction. In other words, the redisplayed cross-sectional image did not make it possible for a user to accurately grasp the cross-sectional image as to which position the transmitting and receiving unit actually moved to in the axial direction of the blood vessel after the radial operation was started.
Consequently, for example, even in a case in which visualization of a detailed cross-sectional image is demanded by carrying out a radial operation and thereafter, by presuming a disorder region based on the re-displayed cross-sectional image and by carrying out again a radial operation at the position of the presumed disorder region, it is not possible for the user to comprehend the accurate position of aforesaid disorder region and there was a problem that it was not possible to move transmitting and receiving unit to aforesaid position accurately.